The present invention relates to optical plastic materials comprising an unsaturated compound having a triphenylsilyl group as a comonomer component.
As the optical plastic materials, polymethyl methacrylate, polycarbonates, diethylene glycol bisallyl carbonate (CR-39), etc. have been proposed.
However, poly(methyl methacrylate) and polycarbonates cannot be cut or polished easily, since they are thermoplastic linear polymers.
Further, the CR-39 resin has defects that its refractive index is as low as 1.50 so that the thicknesses of the center and the edge of the lens are inevitably high unfavorably when lens was made of CR-39 resins.
Under these circumstances, optical plastic materials having a three-dimensional reticulate structure and a high refractive index are required and various techniques have been proposed such as those described in Japanese patent application Kokai publication Nos. 60-231711, 60-231712, 60-231713, 60-197711 and 60-28413.
However, the optical plastic materials disclosed in the above-mentioned five patents often have a poor weather resistance and particularly when a halogen atom or the like is introduced therein in order to increase the refractive index, the materials are colored yellow by the exposure over a long period of time.
On the other hand, polymers containing silicon have generally excellent thermal resistance and weather resistance and a high transparency. After investigations made for the purpose of using the silicon-containing polymer as an optical plastic material, the inventors produced compounds containing silicon and a polymerizable group by introducing an aromatic ring therein. The inventors have found that these monomers are copolymerizable with general-purpose monomers such as CR-39 monomer, diallyl phthalate and diallyl terephthalate to form copolymers having a high refractive indices. The present invention has been completed on the basis of this finding.